vi INTRODUCTION. 



These preliminary considerations are necessary in order to have a clear understanding 

 of the extent and limits of the Animal Kingdom, but\they do not full within those limits; 

 and M ill not therefore have to be reverted to in the sequel of this article. The animal 

 kingdom comprises animals only in their living state ; and, as such, the knowledge of it is 

 ZOOLOGY, or " The Science of Life." Zoology admits of ready and obvious division into three 

 parts. First, the structure of the organs of animals, the science of ANIMAL, ANATOMY, 

 or, as the general science was first appropriated to the structure of men, COMPARATIVE 

 ANATOMY. Secondly, the uses, functions, and actions of the organs in their combination, 

 with the differences of form and habit thence arising, and also the relations of the several 

 animals to each other and to the rest of the material creation, the knowledge of which consti- 

 tutes the science of ANIMAL PHYSIOLOGY. Thirdly, the external appearances of animals 

 their habits, general economy, haunts, numbers, and distribution over the earth or in the 

 waters. This is the portion of the general knowledge of animals, which is open and inviting 

 to the knowledge of all mankind, and which, though it cannot be intimately and thoroughly 

 understood without a knowledge of the other branches, is yet so extensive and so inviting, 

 that there are few who do not more or less attend to and understand it. There is no name 

 except the general one of ZOOLOGY which properly applies to the whole of it; for NATURAL 

 HISTORY, as being equally applicable to all nature, is less precise. It is subdivided into 

 various sciences according to the forms, characters, and habits of the different animals ; and 

 it is the arrangement of those branches of the description of animals, so as to accord as accu- 

 rately as possible with the differences and agreements that are actually to be found in nature, 

 which constitutes the value and advantage of a system of animated nature, or a statistical 

 table of " the animal kingdom," by means of which the various classes or subdivisions 

 may be more easily known and more clearly understood, in themselves singly, and in their 

 relations to each other and to the whole. There are, indeed, two other divisions of the 

 science of animals, which are highly interesting ; but which perhaps require to be treated 

 separately, DOMESTICATION of ANIMALS, AND PROGRESSIVE ZOOLOGY. The first of these 

 is a branch of popular and practical knowledge, and probably the most useful in the whole 

 range of zoological science. The other is of a more speculative character ; and our informa- 

 tion on it is exceedingly vague and imperfect, especially upon the very points upon which 

 it would be most desirable to be informed. It relates to the changes that have, in the lapse 

 of years, taken place in the numbers, the localities, and the species of animals ; which races of 

 them have become extinct, and when, and by what means ; and whether any new ones have 

 come in their place, and if any, which, and by what means. To assist us in the first branch 

 of that inquiry, the data are obscure and few. The remains of the lost animals which appear 

 to have inhabited the land, are deep in the earth, and those of some of the former tenants of 

 the waters (if analogy of structure is to be any guide, and other than that we have none) 

 are often found on the mountains at miles above the present level of the sea. On the other 

 branch of the subject, we are without any guide, and all that we can say is, that, as far as 

 our observation goes, there is not in the productive powers of existing animals any means of 

 producing a new species ; and we know of no source whence any animal can be produced, 

 but by parent animals of the same species. The species is, indeed, somewhat plastic under the 

 hand of natural circumstances, or the resources of art ; and may be broken into varieties 

 differing much from each other in external appearance and in disposition ; but still there 

 appear to be specific bounds which no art, and not even nature itself, can pass. 



